1. Field of the Invention
The present invention relates to a method for correcting measurement errors and an electronic component characteristics measuring device. More particularly, the present invention relates to a method for correcting measurement errors and an electronic component characteristics measuring device that calculate an estimated value of electrical characteristics that would be obtained if measured in a state in which an electronic component is mounted on a standard measurement jig from a result of measuring the electrical characteristics in a state in which the electric component is mounted on a test measurement jig.
2. Description of the Related Art
Conventionally, an electronic component that does not have a coaxial connector, such as a surface-mounting type electronic component, may be mounted on a measurement jig having a coaxial connector, and the measurement jig may be connected to a measuring device via a coaxial cable, so as to measure the electrical characteristics. In such a measurement, variations in the characteristics among individual measurement jigs and variations in the characteristics among individual coaxial cables and measurement devices cause measurement errors.
In a coaxial cable and a measurement device, by connecting a standard device having standard characteristics to the measuring device via the coaxial cable for making measurements, the errors on the side closer to the measuring device than the tip end of the coaxial cable connected to the standard device can be identified.
However, in a measurement jig, it is not possible to identify precisely the errors of electrical characteristics between the connection terminal of the portion on which the electronic component is mounted and the coaxial connector for connecting to the coaxial cable. Also, it is not easy to make adjustments so that the characteristics among the measurement jigs are equal or substantially equal to each other. In particular, it is extremely difficult to adjust the measurement jigs so that the characteristics among the measurement jigs are equal or substantially equal to each other in a large bandwidth.
Therefore, a relative correction method is desired in which correction data obtaining samples are mounted on a plurality of measurement jigs for making measurements, and an equation that corrects the relative errors between a certain measurement jig (hereinafter, referred to as a “standard measurement jig”) and another measurement jig (hereinafter, referred to as a “test measurement jig”) is determined in advance from the variations in the measurement values among the measurement jigs, whereby, from a measurement value of electrical characteristics of an arbitrary electronic component obtained in a state in which the electronic component is mounted on the test measurement jig, an estimated value of the measurement value that would be obtained if measured in a state in which the electronic component is mounted on the standard measurement jig is calculated using this equation.
For example, the standard measurement jig is used to ensure electrical characteristics to users, and the test measurement jig is used to measure and select good products in a step of manufacturing electronic components.
Specifically, for each port, a scattering matrix obtained by synthesizing a scattering matrix ST that removes test measurement jig errors with a scattering matrix of standard measurement jig errors (this is referred to as a “relative correction adaptor”) is determined. By synthesizing the relative correction adaptor with a scattering matrix of a test measurement jig measurement value, an estimated value of the standard measurement jig measurement value is calculated. The relative correction adaptor can be calculated from a result of measuring at least three one-port correction data obtaining samples (such as Open, Short, and Load) in both of the standard measurement jig and the test measurement jig for each port (see, for example, Japanese Patent No. 3558074, GAKU KAMITANI (Murata Manufacturing Co., Ltd.) “A METHOD TO CORRECT DIFFERENCE OF IN-FIXTURE MEASUREMENTS AMONG FIXTURES ON RF DEVICES” APMC Vol. 2, pp. 1094-1097, 2003, and J. P. DUNSMORE, L. BETTS (Agilent Technologies) “NEW METHODS FOR CORRELATING FIXTURED MEASUREMENTS” APMC Vol. 1, pp. 568-571, 2003).
However, the above-described relative correction adaptor does not treat leakage signal components that are directly transmitted between the ports of measurement jigs and are not transmitted to the electronic component connected between the ports as a factor to be corrected. For this reason, correction errors will remain due to the leakage signal components that are present in a significant amount in the measurement jigs.
Such correction errors necessitate an increase in the margin for determining good or bad products in the selection step by the amount of the correction errors, thereby causing a decrease in the yield ratio.
Moreover, according as the continued reduction in the size of electronic components, the distance between the ports will be reduced, and the leakage signal components of the measurement jigs for measuring the electronic components will be increased, whereby the correction errors will also inevitably increase. For this reason, it will not be sufficient to merely increase the margin for determining good or bad products, leading to a possibility that the determination of good or bad products itself cannot be performed in the selection step.